These files contain topographic and bathymetric lidar data collected by the Compact
Hydrographic Airborne Rapid Total Survey (CHARTS) system along the Lake Huron coast
of Michigan in Huron, Sanilac, and St. Clair Counties during August 12-17, 2008. CHARTS
integrates topographic and bathymetric lidar sensors, a digital camera, and a hyperspectral
scanner on a single remote sensing platform for use in coastal mapping and charting
activities. Data coverage generally extends along the coastline from the waterline
inland 500 meters (topography) and offshore 1,000 meters or to laser extinction (bathymetry).
The topographic lidar sensor has a pulse repetition rate of 9 kHz at 1064 nm (near-infrared
wavelength). The bathymetric lidar sensor has a pulse repetition rate of 1 kHz at
532 nm (green wavelength). Native lidar data is not generally in a format accessible
to most Geographical Information Systems (GIS). Specialized in-house and commercial
software packages are used to process the native lidar data into 3-dimensional positions
that can be imported into GIS software for visualization and further analysis. Horizontal
positions, provided in decimal degrees of latitude and longitude, are referenced to
the North American Datum of 1983 (NAD83). Vertical positions are referenced to the
NAD83 ellipsoid and provided in meters. The National Geodetic Survey’s (NGS) GEOID03
model is used to transform the vertical positions from ellipsoid to orthometric heights
referenced to the North American Vertical Datum of 1988 (NAVD88). Upon receipt at
the NOAA Coastal Services Center, the data were converted to las format and to ellipsoid
heights using GEOID03 for data storage and Digital Coast provisioning purposes. Additionally,
the bathymetric lidar data points were classified according to the ASPRS LAS 1.2 classification
scheme as 11 (bathymetry) and the topographic last return lidar data points were classified
as 1 (unclassified).